1. Field of the Invention
This invention relates to a disc cartridge, and more particularly to a disc cartridge which is adapted to rotatably receive a disc-like medium such as a magnetic disc, a floppy disc, a hard disc, a cleaning disc, an optical disc, a photo-magnetic disc or the like therein for recording and/or reproducing.
2. Description of the Prior Art
In general, a conventional disc cartridge is so constructed that a floppy disc, a compact disc, a video disc or the like used for a digital-data storing unit, a video unit or the like is rotatably received in a casing for protection against damage and dust to assure its safety in both use and non-use. Also, in the conventional disc cartridge, the casing is provided on each of upper and lower inner surfaces thereof with a sheet-like liner so as to be contacted with a surface of the disc.
In the conventional disc cartridge, a recess provided on each of the upper and lower inner surfaces of the casing for constituting a disc receiving section is formed into a substantially flat shape and is provided thereon with elongated projection-like ribs, which serve to pressedly contact the liner with the surface of the disc.
Such construction of the conventional disc cartridge causes the disc to be locally pressed by means of the elongated projection-like ribs, so that the disc and liners may be substantially damaged, resulting in an cleaning effect of the liner and a satisfactory contact of the liner with the disc being deteriorated, as well as the disc being unserviceable.
Further, in the conventional disc cartridge, a portion of a casing on which a slide area is defined is substantially reduced in thickness when a shutter is made of a plastic material, because formation of a shutter by a plastic material requires to significantly increase a thickness of the shutter for ensuring its rigidity and smooth operation. Unfortunately, this leads to deterioration of formability and/or workability of the casing.
Such disadvantages as described above are somewhat eliminated by techniques disclosed in Japanese Utility Model Publication No. 44540/1982, Japanese Utility Model Application Laying-Open Publication No. 201667/1982, Japanese Utility Model Application Laying-Open Publication No. 201669/1982 or Japanese Utility Model Application No. 93872/1986.
Unfortunately, the techniques disclosed fail to effectively prevent entrance of a foreign matter such as dust, moisture or the like into the casing by suction due to rotation of a disc in use, because they cannot block a communication between an exterior of a cartridge and its interior through a head inserting hole. Also, they fail to provide a casing, particularly, a portion of the casing on which a slider is movably fitted with rigidity sufficient to fully prevent any deformation of the portion. Further, the techniques cause insufficient cleaning, resulting in dust often remaining on a disc.
Thus, the conventional disc cartridge is highly deteriorated in durability and reliability.
Accordingly, it would be highly desirable to develop a disc cartridge which is capable of ensuring safety of both a disc and a casing in both use and non-use to permit the cartridge to exhibit satisfactory durability and reliability.